The present invention relates to automotive vehicle drive trains and, more particularly, to a power transfer device having a cover threadably attached to a housing.
Vehicular power transfer devices are typically operable to transfer power from an input through a gear set to at least one output. One type of power transfer device is a driving axle assembly. Driving axle assemblies are typically constructed to include a carrier housing rotatably supporting a gearset such as a differential assembly. The carrier housing includes an access aperture to allow the pinion gear and the differential assembly to be positioned within the carrier housing. Some assemblies include a cover pan typically constructed from stamped steel to close the access aperture and maintain lubricating fluid within the carrier housing. The cover pan typically includes a radially extending flange with many fastener apertures extending through the flange. Commonly known carrier housings include a corresponding number of tapped holes spaced about the periphery of the access aperture. Threaded fasteners are disposed through the fastener apertures of the cover pan and threadingly engaged with the carrier housing to sealingly couple the cover pan to the carrier housing.
The costs to create such a sealed connection between the cover pan and the carrier housing may be prohibitive. Specifically, it is costly to drill and tap a plurality of precisely positioned holes in the carrier housing. Furthermore, a substantial tooling expense exists to handle the fasteners and consistently apply a desired torque to the fasteners. Typically, a multi-spindle nut runner would simultaneously apply torque to the fasteners. Furthermore, difficulties may arise in attempting to create a seal between the flange of the cover pan and a face of the carrier housing. Surface finish and flatness characteristics of the mating surfaces must be properly controlled. Lastly, the known flange attachment method used to couple the cover pan to the carrier housing typically does not provide a load path through the cover pan. Accordingly, the carrier housing must be designed to transfer operating loads while having a relatively large access aperture.
Therefore, a need in the art exists for an axle assembly which may exhibit improved cover sealing and may be assembled in a more cost-effective manner.